Brewery- and Beer-Spoilage-Related Gram-negative Bacteria: The Unpleasant, The Malodorous and The Outright Fetid
Barry Ziola and Jordyn Bergsveinson
from: Brewing Microbiology: Current Research, Omics and Microbial Ecology (Edited by: Nicholas A. Bokulich and Charles W. Bamforth). Caister Academic Press, U.K. (2017) Pages: 275-288.
As emphasized by the chapter title, growth of selected Gram-negative bacteria in beer results in an unpalatable product, leading to consumer complaints, and loss of brewer and brand loyalty. Aerobic Gram-negative bacteria historically have been a major problem for brewers, but with improved packaging methods resulting in reduced oxygen levels in beer, these bacteria now are mostly found in improperly attended draft beer systems. Concurrently, reduced oxygen in packaged product resulted in emergence of the anaerobic Gram-negative spoilage bacteria, particularly those within the genera Megasphaera and Pectinatus. Little is known about the genetics of these anaerobic bacteria, given that minimal omics-based research has been done on them. This chapter presents the historical aspects of brewing-related Gram-negative bacteria, where the anaerobic brewing-related bacteria likely originate from and where they are found within breweries, and the evolution of molecular-based approaches for the rapid detection and identification of these bacteria for brewery quality control. Finally, application of metagenomics, genomics, and transcriptomics for improved understanding of brewing-related Gram-negative bacteria is discussed from the perspectives of bacterial persistence within breweries as well as growth in and spoilage of beer read more ...